Means for flowing wells



o. E. DEMPSEY 2,396,162.

MEANS FOR FLOWING WELLS Filed Aug. 24, 1942. 5 Sheets-Sheet 1 Mmh 5,1946.

INVENTOE.

Oscar 3 Dempsey ATTQENEK Fig I.

March 5 1946.

O. E. DEMPSEY MEANS FOR FLOWING WELLS Filed Aug. 24, 1942 5 Sheets-Sheet 2 March 5, 1946. o, E. DEMPSEY 2,396,152

MEANS FOR FLOWING WELLS Filed Aug. 24, 1942. 5 Sheets-Sheef, 5

Oscar E. flew ea 'March 5, 19 46. V o. E. DEMPSEY MEANS FOR FLOWING' WELLS Filed Aug. 24, 1942 5 Sheets-Sheet 4 Fig/7 -PatentedMar. 5,

*UNITED STATES PATENT OFFICE MEANS FOR FLOWING WELLS Oscar E. Dempsey, Tulsa, Okla.

Application August 24, 1942;:Scrlal No. 458,107

11 Claims. (Cl. 103-231) This invention relates to improvements in means for flowing wells, and more particularly but not by way of limitation, to maintain a substantial continual flow of well fluid from the production strata without interference from the lifting medium.

Many' present day automatical intermitting units 'such as wire line plumb bob types move the valve to open position to allow motive pressure fluid to slug the hydrostatic head of oil to the-topof the well, and the motive pressure fluid remains in the eduction tubing as a counteracting pressure against the bottom hole pressure of the well which, must necessarily be bled oil! to the topof the well prior to an efllcient emission of oil from the production strata into the eduction tubing. Furthermore, in intermitting units having a one step slugging operation for the hydrostatic head of 011, all the oil is not displaced from the educdetriment of such a counteracting pressure against the production strata pressure is to decrease the differential pressure across the production strata thereby dissipating the pressure of the well, which in turn decreases the emission of the oil into the eduction tubing.

It is therefore an important object of this invention to displace oil from a well in such a manner to conserve the bottom hole pressure of the well in order to maintain a substantially constant emission of well fluid from the sand strata whereby oil can be continually emitted into the eduction tubing without regard to intervals of time.

And still another object of this invention is to bleed off supply pressure fluid from a small section of the well depth from which oil from the sand strata is displaced therefrom, said bleeding allowing expeditious and repetition flow of oil from the strata into said displacement chamber, thereby eliminating considerable intervals of timewhich oil may be displaced.

And still another object of this invention is to allow escape of formation gas to the well surface at all times except a momentary period when'oil is being displaced or slugged to the top Ofthe well, eliminating any back pressure or sand pressure.

And still another object of this invention is a quantities from a lowermost collection chamber to a reservoir disposed above, which upon a predetermined quantity received would be intermittently slugged therefrom by the; same inlet pressure gas in greater quantities but at the same pressure.

And an additional object of this invention is the economic use of small volumes of gas in cubic feet for progressively lifting small amounts of fluid into a reservoir to be intermittently slugged in predetermined quantities, thereby eliminating the use of large volumes of gas to slug small amounts of entrapped all all the way through the tubing string. e

Other objects and advantages of the invention will be evident from the following detailed description read in conjunction with the accompanying drawings which illustrate my invention.

In the drawings:

Fig. 1 is a fragmentary sectional view showing part of the unit disposed in a well bore.

Fig. 1A is an extension of Fig. 1 showing the lower portion of the unit disposed in the well bore.

Fig. 2 is a vertical sectional view of the lifting unit removed from the well annulus.

Fig. 3 is a view taken' on lines 3-3 of Fig, 2.

Fig. 4 is a view taken on lines 4-4 of Fig. 2.

Fig. 5 is a view taken on lines 5-5 of Fig. 2.

Fig. 6 is a view taken on lines 8-8 of Fig. 2.

Fig. 7 is a view taken on lines of Fig. 2.

Fig. 8 is a view taken on lines 8-8 of Fig. 2.

Fig. 9 is a view taken on lines 8-8 of Fig.2.

Fig. 10 is a view taken on lines Ill-Ill of Fig. 2.

Fig. 11 is a view similar to Fig, 2 showing a closed position of the lower valve unit.

Fig. 12 is a vertical sectional view of the lowermost portion of the lifting unit housing.

Fig. 13 is a view taken on lines i3-|3 of Fig. 12. Fig. 14-15 a view taken on lines l4l4 of Fig. 12. Fig. 15 is a view taken on lines l5l-5 of Fig, 12. Fig. 16 is a view taken on lines [8-4 6 of Fig. 12. Fig. 17 is a vertical sectional view of a modified form for the lower valve intermitting unit.

Fig. 18 is a view taken on lines' l8-l8 of Fig. 17. Fig. 19 is a vertical sectional view of the lowermost portion of the lifting unit shown .in Fig. 1A, Fig. 20 is a schematic view showing the flow passageway of the unit with the valves in one position;

Fig. 21 is a similar view with the valves arranged in another position.

Fig. 22 is a schematic view tion shown in Fig. 17.

Referring to the drawings in detail particu larly Figs. 1 and 1A reference character 2 represents a string of tubing disposed in spaced relation to the well easing 3 extending to the subsurface producing strata of the well. A packing for the modificaassembly 4 is connected to thextubing 2 by a collar 5, and comprises an outer cylindrical housing 6 having its outer periphery provided with a plurality of spaced annular packing glands 1. Below the packing glands the housing 6 is pro vided with a pair of diametrically opposed belly springs 8 having serrated slips 9 securing the assembly in the well casing. The springs are secured to the housing 6 by welding or the like. The cylindrical housing is provided with a longitudinal port in providing communication with the chamber ll between the tubing 2 and casing 3 for the discharge of production and formation gas as will be hereinafter explained. A ball check valve I2 is provided in the upper portion of passageway 10 for formation gas discharging therethrough to the interior of the tubing 2. A string of tubing [3 is disposed in the housing 6 in spaced relation thereto. Packing I4 is interposed between the tubing 13 and inner periphery of housing 6.

A plurality of annular spaced apertures I5 provide communication between a chamber I6 containing motive fluid, and a chamber l1 between the inner tubing l3 and the inner periphery of the housing '6. The chamber l1 acts as a passageway providing communication for motive fluid into the lifting unit is as will be hereinafter explained. The tubing I3 is connected by collar I9 to a lower tubing string 28' of larger diameter extending into a seating cavity 2! of housin 22 for the unit l8. Extending from the lowermost portion of housing 6 is an intermediate string of tubing 23 arranged in spaced relation between casing 3 and tubing 28. The tubing 23 extends to the housing 22 and is welded to a shoulder 24 thereof, in order to support the housing 22 and lifting unit I 8 in the well casing. An annular flange or projection 25 is provided on housing 22, and has secured thereto by welding, or the like, a. tubing 26 extending below the casing into the well bore in proximity of the shot hole. The interior of tubing 26 acts as a filling chamber 21 for oil or fluid to be lifted from the well as will be hereinafter referred to. The lowermost portion of tubing 26 is provided with a seatin nipple 28 welded thereto, which in turn is provided with a perforated hollow plug or gas anchor 29 for a purpose as will be hereinafter referred to.

The lifting unit i anchored in the housing 22 by packing 32 surrounding a cylindrical housing 30 having a fishing neck 3|. A string of tubing '33 of decreased diameter extends from the lowermost portion of housing 38 into threaded connection with a cylindrical housing 34 anchored by packing rings 35 in the nipple 28. As shown in Fig. 19, a standing valve 36 is provided in housing 34 for a purpose as will be hereinafter referred to. A differential valve unit 31 is arranged in the housing 38, while a second valve unit 38 is arranged immediately below unit 31 for a purpose as will be hereinafter referred to.

Motive fluid pressure is constantly maintained in the well from a surface compressor or like equipment (not shown) into chamber i6, through apertures i5, passageway i1, and into lifting unit i8 through a plurality of annularly spaced ports 39 in housing 22, said ports 39 communicating with complementary ports 48 provided in cylindrical housing 38. From ports 40 motive fluid is discharged into conduit ii in communication with valve units 31 and 38 (see Figs. 1A and 12).

Oil or fluid flowing from the production strata through the member 34 is discharged into chamber 21 through ports 46. Motive fluid discharging into the chamber 21 from ports 45 forces oil therefrom through ports 41 upward through tubhousing 22 allowing displacement of fluid from chamber 21 into chamber 5| provided by tubing and acting as a reservoir for storing the well fluid. It will be apparent that the length of tubing providing reservoir chamber 5! is much longer than the tubing providin filling chamber 21 in order to create an increased storage chamber as compared to the lower chamber 21. In practice it has been found that a ratio of 10 to 1 is satisfactory.

Referring now to the valve unit 38 (Figs. 2 to 11 incl.) confined within the outer cylindrical housing 30, a cylindrical manifold 52 is disposed within the housing and extends substantially throughout the valve unit 38. In the upper portion of manifold 52 is a valve housing 53 in which is loosely disposed an elongated main valve 54. The lower end of the housing 53 received a threaded collar 55 carrying a pair of latch members 56 secured therein by studs 51. The collar 55 has a pair of diametrically opposed slots 55a (Fig. 5) to allow free movement of the lower ends of the members 56 toward and away from the manifold 52 for a purpose as will be hereinafter explained. A cylindrical slide valve 58 is disposed in the manifold 52 below the members 56. Slideable in th valve 58 is a cylindrical piston valve 59 wholly confined within the outer valve 58. Below the lowermost end of the valve 58 and manifold 52 is a statio-naryhousing 68 in which is flxedly arranged a cylindrical sleeve 6| having a bore 62. Immediately below the sleeve 6! is a liquid discharge valve 63 adapted to travel between the bottom of sleeve 6i and shoulders 64 provided in housing 60. A nut 65 is secured to the lower end of the housing 38 to secure the unit 36 immediately below the unit 31 in complete assembly (as shown). A cylindrical member 65a supported by the nut extends downwardly therefrom and receives the packing 32.

Referring to the upper portion of the unit 38;

immediately below the valve 54 is a valve push rod 66 having an upper shaft 61 and a lower shaft 58. The push rod 65 extends loosely through an aperture 69 of collar 55 and downwardly between the latch members 56 into the interior of the cylindrical valve 58. A sleeve 10 loosely surrounds the lower shaft 68 and is provided at its top with a V-shaped groove 1| for a purpose as will be hereinafter described. The sleeve 10 is provided with shoulders 12 for anchoring one end of a spring 13 having its opposite end resting on a surface 14 of valve 58.

Figs. 2.and 11 show the different operating positions of the valve unit with Fig. 2 showing the upper valve 54 in open position while Fig. 11 shows how such valve in closed position along with the complementary positions of the auxiliary valves. In the operation of the valve unit, motive pressure fluid is directed through conduit 4! from passageway l1 upward to the top of the valve unit 38 through an apertured baffle member 15 interposed between top valve unit 31 and lower unit 38.

As shown in Figs. 2 and 11, particularly Fig.

11, supply pressure fluid passes through the aperaired baffle is into. a bleed port 1a m valve 54 and leaks between the valve 54 and its bore through aperture 69 into chamber 18 provided by manifold 52 between valves 54 and .59. It is to be understood that theflt of the valve 54 in its bore, especially the short periphery of the In this position the differential pressure across I the valve 59 has been decreased (as will be hereinafter explained) so that the pressure aided by tension spring 13 causes movement of piston valve 69 downward until valve port 19 moves past a port 88 provided in slide valve 58 thereby preventing escape of the fluid therefrom. Leakage pressure flowing into chamber 18 will continue the movement of the valve 59 downward to where the bottom face 8| contacts the top of valve sleeve 82 .which in turn contacts follower rod 83 to move pilot valve 63 downward past ports 49a and 49b providing communication between passageways 49 and 50. Continued downward movement of valve 59 causes it to contact the apertured base 84' of valve 58 thereby moving valve 58 downward out of contact with the latch members 56. The valve 58 i held by friction and does not move downward of its own weight during the preliminary movement of the valve 59. During initial downward movement of valve 59,-the sleeve 19 is prevented from moving downward by the tension of the spring 13. As soon as the top of valve 58 moves below the shoulders 85 of the latches 56 (Fig. 2), the latch members are free to swing outward .toward' the manifold 52 thereby allowing downward movement of the shaft 61 of the push rod 66. Push rod 86 i then moved downward by valve 54 actuated by supply pressure fluid. Downward movement of valve 54 to open position (as shown in Fig. 2) opens ports 81 to supply pressure fluid which is directed from ports 81 downward through a passageway 88 (Fig. 4 in manifold 52 to be discharged into a chamber 89 below the base 84 ,of slide valve 58 (see Figs. 2 and 8), said passageway 88 communicating with chamber 89 through port 98 provided in manifold 52 (Figs. 8 and 11). From chamber 89 supply pressure fluid is discharged through port 8| communicating with a passageway 43 provided in manifold 88 and extending downward (see Figs. 13 to 16) into communication with ports 45 and discharged into the bottom chamber 21.

However,. with the upper-,valve 54 in open position (Fig. 2) the lower valve 63 has been moved downward to close port 49a. In order for the supply pressure fluid to displace well fluid from chamber 21 and through ports 49a, it is necessary to move the unit 38 u'p'ward into a position shown in Fig. 11. .In order that valve 83 will be moved upward. the differential pressure maintained on both sides of the valve 83 must be greater than the differential pressure between chambers 18 and 88. It will be understood that the relationship of pressures are commensurate with the areas of the various pistons .or piston valves and the ratio between them is a matter of choice dependent upon a particular well. The manifold 58 has a small port 6841 providing communication between port 49a (Fig. 10) and the chamber 83a. These ports measure the reservoir pressure in order to determine the difierential across the valve 83. With the valve 83 closed and valve 54 opened (Fig. 2) it is to be noted that the latch members 56 are swung outwardly and prevent any upward movement of valve 58 as long as valve 59 remains in its lowermost position. With an increase of differential pressure across valve 63 pressure fluid and liquid in chamber 21 moves valve 63 upward to allow displacement of liquid through discharge port 49b. Simultaneous with upward movement of valve 63, rod 83 (Fig. 2) and follower 82 are moved upward to move piston valve 58 upward to a point where port 18 moves into communication with port 88 (Fig. 11) which inturn communicates with passageway 88 throughports 88a. It will be apparent that with motive pressure fluid imposing a downward thrust acrossthe top of valve 59, a similar upward thrust must be produced to overcome the first mentioned thrust if the valve parts are to move upwardly. As the chamber 88 assumes greater pressure, the pressure differential across the valve 59 between the chambers 18 and 89 is decreased. Furthermore, the pressure at 88 corresponds with the pressure within lower chamber 21, and said pressure influences the bottom face of valve 83 either through the medium of entrapped liquid or by direct correspondence. As heretofore stated, since the input pressure is to be greater than the pressure existing at 63a, a pressure condition will be approached and quickly passed in chambers 88 and 21 enabling the increasing upward thrust against pilot valve 63 to overcome the diminishing downward thrust against valve 59. With the valve 59 moved to this position pressure fluid within the chamber 18 is bled or discharged to passageway 96 thereby decreasing the differential between chambers 18 and 89. The upward movement of piston valve 59 simultaneously moves push rod 65 upward which in turn moves valve to an up or closed position thereby blocking off ports 81 and 88. The closing of valve 54 moves the large diameter shaft 61 of rod 66 out I of the unit 38' (Fig. 11) well fluid has been displaced through the outlet ports 49b to the reservoir 50, and immediately subsequent the valve 59 has been moved upwardly to bring port 82 in communication with ports 88a and allow a predetermined rate. of exhausting or bleeding off of the residue motive pressure fluid which caused the displacement of the wellfluid. It will be apparent in this operation that the upper valve 54 is closed and locked by the latch members 56.

With substantially all the well fluid displaced fromthe filling chamber 21, it is necessary .to bleed off residue motive pressure fluid from the chamber in order that the bottom hole pressure of the well will continue to discharge well fluid into the chamber. With the exhaust of supply pressure fluid from chamber 21, the differential between chamber 18 and chamber 89 is decreased to such an extent that tension spring 13 exerts force to cause downward movement of valve 58 thereby closing off port 19 from passageway 98. In this condition the constantly maintained supply pressure through apertured bafile 15 discharges through bleed port I6 and leaks between the valve 54 and its bore into chamber I8, and with the closing off of port I9 immediately builds up pressure to cause continued downward movement of piston valve 59 as heretofore explained.

;This increase of pressure in chamber I8 likewise acts against the top portion of slide valve 58 to start its movement downward in conjunction with piston valve 59 contacting the top face of base 84 thereof, thereby unlocking the latches 59 from a position shown in Fig. 11 to a position shown in Fig. 2, and thus allowing downward movement of piston valve 54 to open position and discharge of pressure fluid into passageways 88 and 43, as heretofore described.

The formation gas from the sand strata is liberated from the well through chamber II along with the used or residue supply pressure fluid exhausting through passageway 96; These gases are discharged into the tubing 2 through the check valve I2. From Fig. 2, it will be apparent that supply pressure fiuid during the operation of the valve unit 38 simultaneously flows through passageway II to be constantly maintained at the top of the valve unit 31. In this manner inlet pressure fluid is maintained in chamber I to keep valve IOI disposed in a lowermost position of'valve housing I02. Housing I02 is provided with a port I03 communicating with a passageway I04 which in turn communicates with a chamber I05 arranged in the unit housing I06, and in which is disposed at lower valve I0I. With pressure fluid acting against the underface of valve I0? from apertured bafile I0, and simultaneously, flowing through passageway I00 into chamber I05, it will be apparent there is an equal pressure on both sides of the valve I0'I whereby tension spring I08 maintains it in a lowermost position. With the valve unit 31 maintained in this position, motive fluid is continually directed through unit 38 to displace oil from chamber 21 into the reservoir chamber 5I which communicates with a chamber I09 below valve IOI through a passageway I I0.

With a sufficient increase in hydrostatic head in the reservoir chamber 5i complementar with an increase in chamber I09 and assisted by the tension spring III, the motive pressure fluid at the top of the valve IOI is overcome causing the valve to move vertically upward and close off the port Iild, and open a lower port I I2 communicating with passageway IM. With the valve IOI moved to an upward position supply pressure fluid in chambers I05 is allowed to bleed oil? through the passageway IMinto chamber I 09 thereby u.n balancing valve I01 by relieving pressure on one side thereof. With the unbalancing of valve I01, supply pressure fluid flowing through apertured baflie I5 is directed through 'ports H3 into chamber 5i for displacing or slugging the well fluid present in the chamber upward to the top of the well. 7

Operation In operation of the preferred embodiment, it will be apparent that motive fluid discharges through ports 39 to cause actuation of the valve unit 38 to flow motive fluid through passageway 88 and 43 through ports 45 into the filling chamber 2i for displacing oil therein that has emitted from the production strata. The oil is displaced through ports 4% by movement upward of the valve 63. From 49b oil flows, through passageway 50 into the reservoir 5I and builds up a hydrostatic head suificient to overcome the static pres ure acting on intermitting unit 37 which functions to slug the oil onto the top of the well. The upward movement of valve 58 allows discharge of residue motive fluid in chamber 21, passageway 43 and chamber 89 through passageway 88 and ports a outward to the top, of the well thereby maintaining the production pressure to provide continual emission of oil from the strata into the chamber 21. Furthermore, during discharge of motive fluid into chamber 21, valve 58 is locked by the latch members 56 (Fig. 2) to prevent bleeding ofFof motive fluid before displacement of oil from chamber 21. Similarly, valve 54 is locked by the latch members (Fig. 11) to prevent flow of motive fluid through unit 38 during the bleeding operation.

From the foregoing, it will be apparent that the invention contemplates the lifting of small quanties of oil from a lower fllling chamber to a higher reservoir to be intermittently slugged.to the surface of the well. The lifting unit functions in such manner to prevent any motive fluid counteracting the bottom hole pressure of the well and assuming a high differential across the strata to provide constant emission of well fluid from the production strata. Furthermore, the lifting apparatus will operate successively in deep wells having considerable production pressure, or with shallower wells having a minimum amount of production pressure to displace the oil with a minimum of motive fluid in a most efilcient and economic manner.

In Figs. 17 and 18 is shown a modification of the lifting unit and more particularly the lower valve intermitting apparatus. It will be apparent from inspection of Fig. 17 that the numerous fluid inlet and outlet ports are disposed in different positions from those disclosed in Fig. 1A of the preferred embodiment. Referring now to Fig. 17, the valve unit 38' receives supply pressure fluid from passageway M, for maintainingthe piston valve I2! in a lowermost or open position (not shown), and in this position, a lower piston valve I22 is prevented from moving upwardlyby a plurality of annular spaced balls I23 arranged between the valves I2I and I22. A valve housing I24 separates valves I2I and I22. Valve IZI is provided with an annular groove I25 comp1emen= tary to an annular groove I26 on valve I22. Housing I24 is provided with a plurality of apertures I21 in which the balls I23 are disposed.

With input pressure fluid acting against the valve I2I to move it downward the balls are moved out of groove I25 through apertures I21 and partially into the groove I20 of valve I22. Ir this position, valve I22 is locked by the balls to prevent any upward movement thereof. It will be apparent aswill be hereinafter referred to, that the balls operate in similar manner to prevent downward movement of piston valve IZI during an up position of valve I22 (Fig..17). During the open position of valve I2I motive fluid is directed through ports I35 (Fig. 18) in housing I24 communicating with an annular groove I36 provided in manifold I31 which in turn communicates with a plurality of axially arranged passageways I38 extending through the manifold I31 to a position below the valve for discharging supply pressure fluid through ports I39 into the filling chamber 21 as in the preferred embodiment. With the valve I2I inopen position (not shown) motive fluid pressure due to the fit of the valve I2I and its bore is allowed to leak there between'to be discharged into the port Hill-A communicating therewith, and then to a communicating port I40 which in turn communicates placing all the entrapped oil therein.

with the eduction tubing, a filling chamber comwith a chamber I28 below the valve. When the pressure in chamber I28 becomes equivalent to the pressure acting on top of the valve I2I, the

valve is moved upwardly as shown in Fig. 1'7, through the assistance of a tension spring I29. The fit of the valve I2I and its bore as well as the ports I40 and I4fl--A can be constructed so that the bleeding into chamber I28 is substantially commensurate with the flow of supply pressure fluid into chamber 21 for substantially dis- In exhausting residue input fluid from chamber 21 after displacement of the oil therefrom, the valve I2I has moved to an up position thereby unlocking valve I22 and allowing pressure fluid in passageway I38 to overcome the tension of spring I4I to raise valve I22 and open port I42 whereby residue" pressure fluid is exhausted through a passageway I43 communicating with the chamber II shown in Fig. 1A of the preferred embodiment. It will be apparent that with valve I22 in up position, the balls I23 have been moved into grooves I25 (not shown) to lock valve I2l as here tofore explained to prevent any downward movement thereof until exhaust pressure is relieved from valve I22 allowing spring I4I to move it downward and unlocking valve I2I The residue pressure fluid discharges from passageway I43, it being understood'that the oil was displaced from chamber 21 through a passageway I provided in manifold I31. Packing I 45 surrounds the manifold I31 as shown in the preferred embodiment. With the residue pressure exhausted from chamber 21 pressure is relieved against the valve I22 whereby tension spring MI moved it to a lower position closing port I42 simultaneously with unlocking valve I2I and opening of ports I35 to discharge supply fluid into passageway I38 and filling chamber 21 for again displacing the well fluid therein. It will be apparent that during the upward movement of valve I 2! pressure fluid in chamber I28 will be. bled off through port I40 and port communicating with annulus I36.

From Fig. 17, it will be apparent that motive pressure fluid during the operation of valve unit 38' simultaneouslyflows through an aperture I41 into the continued passageway M to cause operation of valve unit 31 when the hydrostatic head of fluid increases sufiiciently in chamber as previously described in the preferred embodiment. From Fig. 1A, it will be apparent that the inter-- mitting unit can be run into the well bore and seated in housing 22 on a wire line and set down with a set of conventional jars (not shown). The

flsh neck 3| allows for connection with a wire vention contemplates a'removeable bottom hole intermitting unit for displacing oil.

Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it

being understood that any modification in the precise embodiment of the invention may be made within the scope of the following claims without ,departing from the spirit of the invention.

What is claimed is:

1. In an apparatus for lifting fluid from a well having an eduction tubing an'da well casing, said apparatus including a reservoir communicating munlcating with the well-casing and with the reservoir, means for introducing constantly maintained motive pressure fluid from the casing into the filling chamber for displacing well fluid therein into the reservoir, said means permitting immediate bleeding oil of residue motive fluid from. the filling chamber, said means so constructed and arranged to prevent introduction of motive pressure fluid into the filling chamber during the bleeding off of the residue fluid therefrom. anclmeans responsive to the hydrostatic head of well fluid in the reservoir to direct motive fluid from the casing into the reservoir for slugging the well fluid from the well. I

2. In an apparatus for lifting fluid from a well including a filling chamber, means for introducing constantly maintained motive pressure fluid into the filling chamber for displacing fluid emitting therein from the production strata, means for receiving the displaced fluid, said first mentioned'means permitting bleeding off of th residue motive fluid from th filling chamber, and means independent of the first mentioned means and responsive tothe hydrostatic head of well fluid in the receiving means for introducing motive fluid thereto to slug the well fluid to the top of the well.

3. In a well flowing apparatus including in.

combination with the, well casing and tubing for directing constantly maintained motive fluid into the well, a reservoir communicating with the tubing, 9. filling chamber communicating with the casing and the reservoir, a valve unit communicating with the casing and filling chamber for periodically introducing motive fluid into the filling chamber for displacing well liquid emitting therein from the production strata, said valve unit responsive to the displacement of the well fluid from the filling chamber to allow exhaust of residue motive fluid and formation gas 1n the chamber to a passageway communicating with the tubing, and an independently operated valve unit responsive to the hydrostatic head of well fluid in the reservoir for directing the motive fluid into the reservoir and slugging the well fluid upward in the eduction tubing.

4. In an apparatus for lifting fluid from a, well having an eduction tubing, said apparatus" in; cluding a reservoir communicating with the eduction tubing, a filling chamber communicating with the well casing and with the reservoir, a lifting unit interposed between the reservoir and the filling chamber, said lifting unit comprising uppeer and lower valve units communicating with motive pressure fluid constantly maintained in the well casing, said lower valve unit having means movable to direct motive fluid therethrough into the filling chamber for displacing well fluid therein into the reservoir, and slide valve means in the lower valve unit movable in response to the displacement of well fluid from the chamber to provide communication between the filling chambeer and the eduction tubing whereby residue motive fluid is allowed to bleed oil immediately therefrom, means in the lower unit preventing movement of the first mentioned means for directing motive fluid to the fllling chamber during the bleeding of the residue fluid, said upper valve unit responsive to the hydrostatic head in the reservoir to direct motive fluid thereto for slugging the well fluid to the top of the well.

5. In an apparatus for flowing wells including a filling chamber, means for periodically introducing a constantly maintained motive pressure fluid into the filling chamber in the well for displacing fluid emitting therein from the production strata, a reservoir above the filling chamber for receiving the displaced fluid, said means comprising a valve movable in response to the displacement of the well fluid from the filling chamber to allow bleeding oil of residue motive fluid therefrom, and means in the first mentioned means preventing introduction of motive fluid into the filling chamber during the bleeding oil of the residue motive fluid, and means. operable independently of the first mentioned means and responsive to the hydrostatic head in the reservoir for directing motive fluid thereto to slug the well fluid to the top of the well.

6. In an apparatus for flowing wells including a filling chamber, a lifting unit for introducing a constantly maintained motive pressure fluid into the filling chamber in the well, for displacing oil emitting thereto from the production strata, a reservoir above the filling chamber for receiving the displaced oil, said lifting unit comprising a piston valve movable t direct motive fluid into the filling chamber, a valve in the lifting unit movable in response to the displacement of the oil from the filling chamber to allow bleeding oil of residue motive fluid therefrom, means in the lifting unit preventing movement of the piston valve for introducing motive fluid during bleeding off of the residue fluid from the filling chamber, and means operable independently of the first mentioned means and responsive to the hydrostatic head of oil in the reservoir for'directing motive fluid thereto for slugging the oil to the top of the well.

'7. In an apparatus for flowing wells including a lifting unit for introducing a constantly maintained motive pressure fluid into a filling chamber in the well for displacing oil emitting therein from the production strata, a reservoir above the filling chamber and in communication therewith for receivin the displaced oil, said lifting unit interposed between the reservoir and the filling chamber and comprising a piston valve movable in response to motive fluid to direct motive fluid into the filling chamber, a valve in the lifting unit movable in response to the oil being displaced from the filling chamber to allow bleeding ofl of residue motive fluid therefrom, and means in the lifting unit preventing movement of the valve during the introduction of motive fluid through the lifting unit, and means operable independently of the first mentioned means and in response to the hydrostatic head of oil in the reservoir for directing motive fluid therein to slug the oil to the top of the well.

8. In an apparatus for lifting fluid from a well having an eduction tubing and well casing, said apparatus including a reservoir communicating with the eduction tubing, a filling chamber communicating with the well casing and with the reservoir, means for introducing constantly maintained motive pressure fluid from the easing into the filling chamber for displacing well fluid therein into the reservoir, said means permitting immediate bleeding off of residue motive fluid and formation gas from the production strata present in the filling chamber after displacement of the well fluid, latching means preventing introduction of the motive fluid during the bleeding off of the residue fluid, and means responsive to the hydrostatic head of liquid in the reservoir to direct motive pressure fluid from the easing into the reservoir for slugging the well fluid into the reservoir. l

9. In an apparatus for flowing wells including a filling chamber, aremovable lifting unit for introducing motive pressure fluid into the filling chamber in the well for displacing oil emitting thereto from the production strata, a reservoir above the filling chamber for receiving in the displaced oil, said lifting unit comprising a piston-valve moveable to open a communicating passageway for directing motive fluid into the filling chamber, a liquid discharge valve in the lifting unit moveable in response to the displacement of the oil from the filling chamber to allow bleeding of! of residue motive fluid therefrom, and means in the lifting unit preventing movement of the piston valve for introducing the motive fluid into the passageway during bleeding off of the residue fluid from the filling chamber, and means operable independently of the first mentioned means and responsive to the hydrostatic head oi oil in the reservoir for directing motive fluid thereto for slugging the well fluid to the top of the well.

10. In an apparatus for lifting fluid from a well having an eduction tubing, a reservoir communicating with the eduction tubing, a filling chamber communicating with the well casing and with the reservoir, a valve unit interposed between the filling chamber and the reservoir for introducing constantly maintained motive fluid from the casing into the filling chamber for displacing well fluid therein upwardly to the reservoir, said valve comprising a main valve, means responsive to one position of the main valve for directing motive fluid into the filling chamber, a valve moveable in response to the flow of motive fluid against the liquid in the filling chamber to allow discharge therefrom, a piston valve moveable to bleed oil residue motive fluid from the filling chamber, a slide valve, a rod, a plurality of latch members, said slide valve moveable in response to one position of the main valve to move the piston valve to a closed position relative to exhaust ports for bleeding residue fluid, said rod and latch members maintaining the piston valve in closed position during the introduction of motive fluid into the filling chamber", and means operable independently of the valve unit and responsive to the hydrostatic head of fluid in the reservoir to direct motive fluid from the casing into the reservoir for slugging the well fluid from the well.

11. In a lifting apparatus for lifting fluid from a well including a filling chamber and a reservoir, means for periodically introducing constantly maintained motive pressure fluid into the filling chamber for displacing fluid emitting therein from the production strata to the reservoir, said means allowing bleeding off of residue motive fluid utilized in the displacement of well fluid from the filling chamber and simultaneous- 

